"Latent thiol monomer," as used herein, is defined as a polymerizable monomer containing; at least one functional group polymerizable to form a homopolymer or copolymerizable with at least one first ethylenically unsaturated monomer to form a copolymer; and at least one protected thiol group, for example a thioester, preferably thioacetate. The term "latent" refers to the fact that the protected thiol group does not react in the homopolymerization reaction or the copolymerization reaction with the first ethylenically unsaturated monomer or monomers. After the homopolymerization or copolymerization is conducted, the protected thiol group can be deprotected, for example by a cleaving reaction, to form a thiol group pendant to the polymer chain. This thiol group so formed can then react in a second polymerization with at least one second ethylenically unsaturated monomer, to form a graft copolymer.
"Graft copolymers" as used herein, are defined as the macromolecule formed when polymer or copolymer chains are chemically attached to a polymeric backbone as side chains. Generally, in graft copolymers, the side chains are of different composition than the backbone chain. Due to the ability to chemically combine unlike polymeric segments in one molecule, graft copolymers have unique properties, making them particularly useful for their surface active properties, such as for example in stabilizing physical blends of otherwise incompatible polymeric or monomeric compounds.
The copolymer products of the present invention can be used directly in water-based emulsion coatings, elastomers, adhesives, caulks and mastics. Still further uses for these copolymers are as plastic additives for use as compatibilizers of polymer--polymer blends.